a. Field of the Invention
The invention relates to imaging systems for use in the performance of medical diagnostic, therapeutic, mapping and ablative procedures. More particularly, the invention relates to an imaging system including optical or magnetic tracking for generating accurate 2D or 3D time varying images.
b. Background Art
A variety of imaging systems can be used to assist a clinician or physician in the performance of various medical diagnostic and therapeutic procedures related to different parts of the human anatomy, such as, the heart. Such imaging systems include, for example, those based on a variety of technologies, such as, wands (e.g. ultrasound), (fluoroscopy (e.g., x-rays), computed tomography (CT), magnetic resonance (MR), and intracardiac echocardiography (ICE). For ultrasound wands, an ultrasound emitter may be disposed in the wand, or in the case of catheters (e.g. ICE (intra-cardiac echo) or TEE (transesophageal echo)), the ultrasound emitter may be disposed in the catheter.
In the case of a wand, the wand may be placed on the skin of a patient and typically, 2D image slices may be collected. Alternatively, the wand may also contain a rotating sensor, or the wand itself may be rotated on a mechanical rotation device for collecting 3D images. In both cases, images are continuously collected so that CINE (e.g. real-time animated views) images are possible, thus making the 2D and 3D images, 3D and 4D respectively, with the additional dimension being time.
Based on the data collected by the wand, it is also possible to automatically extract the shape of an internal body structure using automatic segmentation algorithms. By evolving the segmented static models over time, time varying surface models can also be generated.
A drawback of these methods is that the various images collected by the wand are not registered together. In other words, since the ultrasound wand may be moved or tilted, the images from different points of time are not aligned with each other. For example, if parallel images are desired and the ultrasound wand is tilted as images are being taken, the images essentially will not be parallel. Moreover, since the wand can be manually or even mechanically rotated, there can be various gaps in the disparate images.
The inventors herein have thus recognized a need for a system and method for precise and automatic correlation of such images, regardless of whether a wand is manually or mechanically rotated or tilted, thus freeing an operator to move a wand with limited constraints. The inventors herein have also recognized a need for a system and method for providing guidance for such imaging, and a system that is capable of extrapolating omitted image data.